Disney's 1981 film Dragonslayer (IMO the best dragon-themed movie ever made) has no less than 3 scenes with references to transmutation, which I think is a record:

1- Ulrich the sorcerer tells his apprentice Galen that he actually saw a guy named "Balizarius" (or "Balatherius", or something to the effect) turn lead into gold, and laments that he could never do that.

2- Ulrich's servant is trying to conceal his master's "magical ashes" from Galen, who jokingly teases him: "What have you got there, Hodge?... Some gold, eh? What do you say I turn it into lead?" (alchemical humor, brilliant! I don't recall any other movie having alchemical jokes.)

3- After King Casiodorus gains possession of Galen's amulet, he and one of his advisers try to use it to turn lead bars into gold, but the amulet refuses to obey and instead burns the palm of his hand.

Not having to do with alchemy, but yet another of the many great scenes in this movie: when Tyrian (masterfully played by the late John Hallam) confronts Ulrich (also masterfully played by the also late Sir Ralph Richardson) and those who seek his "magical" help without requesting proof of such claims first. A very poignant comment on the claims and "deeds" of magicians/sorcerers/necromancers. A nice short lesson in skepticism and critical thinking.